Surface grinder attachment for milling machines



Aug. 29, 1950 A. P. DREDSKE SURFACE GRINDER ATTACHMENT FOR MILLING MACHINES Filed May 25, 1945 I 'ITLVG i fi T127160 F flreds/re Patented Aug. 29, 1950 UNITED STATES ?ATENT runes SURFACE GRINDER ATTACHMENT FOR MILLING MACHINES Arthur P. Dredske, Rockford, 111.

Application May 25, 1945, Serial No. 595,672

Claims.

1 This invention relates to milling machine attachrnents and is more particularly concerned with new and improved grinder attachments but most of them have been objectionable for one reason oranother and have therefore not been used to any appreciable extent. It is, therefore, the principal object of m invention to provide a more practical and serviceable attachment, which, by reason of its simplicity and compactness of construction, may be produced at reasonably low cost and which, because of the novel Way in which it is constructed and applied to the overarm of the machine and the way in which the motor drive is transmitted to the driven spindle provides a wide range of adjustability and adaptability for different jobs and assures the desired rigidity and relative freedom from vibration so that close accuracy of operation, as required in surface grinding and tool grinding, is obtained.

The invention is illustrated in the accompanying drawing in which Figs. 1 and 2 are a side view and front view respectively of a milling machine showing a grinder attachment made in accordance with my invention applied thereto, and

Figs. 3 and 4 are sections on the correspondingly numbered lines of Fig. 1 on an enlarged scale.

The same reference numerals are applied to corresponding parts throughout the views.

t will, of course, be understood at the outset that the attachments, with which'my invention is concerned, are intended to be sold at relatively low prices as compared with the cost of conventional surface grinders, for application to existing milling machines. There is a real demand for such attachments in many places and particularly in small machine shops, where occasional surface and tool grinding jobs might otherwise necessitate taking that work to some larger shop equipped with a surface grinder. It is the aim of my invention to provide a grinder attachment for milling machines giving substantially the same facility of operation, range of adaptabilit to different jobs, and close accuracy as a regular surface grinder, at a small fraction of the cost of such a machine.

In the grinder attachment, shown at 6' in Figs.

1 and 2, the motor 22' is mounted on a shelf 28 that is free to turn about a vertical axis with the bearing l3 relative to a bracket 36 adjustably supported on a bearing 3!, which, in turn, is adjust-ably clamped on the overarm or bar 1' of the milling machine, whereby to permit rotary ad- -,iustment'of the grinding wheel 20' in a horizontal planaand accordingly. greatly increase the range of usefulness of the grinder attachment. lhe bracket 36 has a pair of parallel guide rods 38 suitably secured thereto, as indicated at 39, and extending therefrom at right angles to the axis of the vertical shaft 49 received in the bracket 36 and forming the axle for rotary adjustment of the bearing l8 and motor 22. The

rods 35 an. slidably received in parallel holes 4! provided in the upper portion of the bearing 31, and have V-grooves 42 provided in the outer sides thereof, which slidably receive V-shaped gibs 43 that are adiustably mounted in longitudinal grooves 44 provided therefor in the bearing 3} in one side of the holes ll. Oneof these gibs 4'2 has a number of screws d5 bearing against the back thereof and adjustably threaded in holes in the bearing 3?, so as to take up excess clearanc'e between the rod 38 and the hole 4! fora close working fit of the rod in the hole, regardless of such wear as may occur. The other gib 43 has screws 45 cooperating therewith in a similar way, but these screws have hand levers 41 attached thereto, so as to permit clamping the rod tightly in an adjusted position. Adjustment of the rods 38 inwardly or outwardly is obtained by the turning of pinions 48, which are provided on a crossshaft 49 and mesh in rack teeth 56 provided on the tops of the rods 38. A bevel gear provided on one end of the cross-shaft Q9 has a bevel gear 52 meshing therewith and carried. on the end of a shaft 53, that is mounted in the top or" the bearing 3'! and is arranged to be turned by means of a hand wheel S iprovided on the outer end thereof. Thus, when the screws it are loosened, in or out adjustment of the rods 38 may be made to secure the proper positioning of the grinding wheel 26', after which the screws 46 may be tightened again, and in that way the attachment is rigidly secured in adjusted position.

The rotary adjustment of the Wheel 20' about the shaft 40 is permitted when the screw 55, which cooperates with a pair of clamping gibs 56 and 51, is loosened by means of its hand lever 58. The gibs 56 and 51 are slidable in a bore 59 in the bracket 36 that is substantially tangent to the vertical bore 60 in said bracket, and the gibs .are in spaced relation and have their adjoining ends beveled off, as indicated at 6 I, on the radius of the bore 60, so that when the screw 55 is tightened, these beveled ends exert a clamping action on the periphery of the vertical shaft 40 sufficient to fasten the bearing l8 and motor 22 quite rigidly in an adjusted relationship to the bracket 36. The lower end of the shaft 40 is pinned, as indicated at 62, to the bearing [8, and there are two thin washer-like nuts 63 threaded on the upper'end portion of the shaft 40 above the bracket 36 to prevent downward displacement of the shaft 40 in the bracket, the lower one of these nuts being adjustedftoitake' upend play in the shaft 40 and the upper nut,..when.- tightened, serving to lock the lower nut.. The

reduced upper end portion 64 of the shaft is received in the socket 65 provided therefor in the: bottom of the shelf 28', and a set screwlifi threads in the wall of the socket 65 and serves when tightened against the reduced upper end portion 64 of the'sha'ft to clamp'tlieshelf 28 in vertically adjusted. relationship to. the shaft, therebyper- 'mitting take-up of slack in the belts 25' that inprojecting lugs 68 provided on the split sleeve -69that'isentered 'ina. bore Hlfin one end of the bearing 31in concentric relation to the bore H provided inthe main body; portion of the bearing, in which the-bar 1 is-received. A split-sleeve 12 of-crescent-shapedcross-section; whose outer periphery is= concentric withand. fits snugly within the bore of the sleeve69- and whose bore isconcentric with the bore-1 l, closely surrounds the bar' l and servesto clamp'the bearing'3'l in adjusted positionwhen the screws 61 are-tight- 'ened. The sleeve 69-being a separate-and distinct-part from -thebearing 3 1, any distortion of the sleeve, therefore, willznot result in transmitting such distortion to the bearing 31. This avoidsv any likelihood of interference with the easyworking of the'rods'38 in the holes 4| The lower rear-portion of the bearing 3l'is of course split, as indicated at 13, to permit extension of the. lugsfia downwardly from .the bearing 31, so that accessmay-be had to the screws 61 when'the bearing 31 istobe clamped-or loosened.

The motor 22. and its supporting 'shelf '28 will approximately counterbalance the weight of the rest of .theattachment'with respect to therbar 1' so that the attachment will operate satisfactorily and with" minimum vibration'in all positions of perform other operations besides grinding, In

thezfeedzmovement of: the table Ill the work'v is ,fedrlongitudinally with-respect to the saddle l", endiinfthe transverse feed movementofzthezlatter 'orrztheWertically-adjustable kneeaii 'the workjs adjusted accordingly: witlrisrespecti torther; wheel 20, so as to present all portions of the surfaces to be ground. The fact that the motor 22 is in balanced relation to the rest of the attachment and all of the weight of the attachment is borne by the heavy bar I minimizes the likelihood of vibration. The usefulness of the attachment for the grinding of tools is indicated in Figs. 1 and 2, wherein I have shown atool TILmounted between centers M on the table II preparatory to the grinding thereof in the back and forth feed movements of the table II.

It is believed the foregoing description conveys a good-understanding of the objects and advantages of my invention. The appended claims have beendrawn to cover all legitimate modifications and'adaptations.

I.claim:

l. Anattachment for milling machines comprising an upright bracket of elongated form having a clamp intermediate its ends on a horizontal'axis for support adjustablyon-thehorizontal overarm of='a-milling-'macliine, 'a substantially horizontal spindle rotatably-mounted" in one end portion of -said bracket and ladapted to carry a tool, such: as a grinding wheel, on one projecting end thereof, an electric motor for driving said spindle 'mounted on the otherend of said bracket in substantially diametrically opposed counterbalancing: relation to said' spindle, said motor having an armature shaft, a drive' connection between the armature-shaftiof said motor and the other: end .of said spindle, apair of spaced parallel rods slidablymountediin holes provided therefor in said clamp'indradially spaced parallel. relation. to. said overarm, said rods 'beingattached atztheir outer ends: to said" bracket for" adjustably supporting said bracketrelative to the. clamp and overarm; racks on said rods-a cross-shaft mountedin said clamp carryin pinions meshing with said racksand manually operable 'means for turning said cross shaft:

2: An attachment for milling machines comprising an upright bracket of elongated form having a clamp intermediate-itsendson=a horizontal axis for support adjustably on the horizontal overarm of a milling machine,-v a substantially horizontal spindlerotatabl-y mounted inone-end portion-of said bracket andadapted to carry a tool; such asa grinding Wheel, on

one projecting 'end thereof, an electric. motor-for driving said spindle mounted, on-the otherend of i said bracket.- insubstantially diametrically opposed counterbalancing relation to'said-spindle, said motor having an armature shaft, a drive connectionbetween-the armature shaft of said motor and theotherend-of said spindle, a pair of spaced parallel rods slidably-mo-unted in holes provided therefor in saidclampin radially spaced-parallel relation to said..overarm, said rods being attached at their. outer endsyto. said bracket for adjustably supporting said bracket relative. to the clamp and overarm,.racks1-on.said rods, a cross-shaftmou-ntedin: said 'clampcarr rying pinions-meshingwitlrsaid racks, and manzontal axis for support adjustably on the horizontal overarm of a milling machine, a substantially horizontal spindle rotatably mounted in one end portion of said bracket and adapted to carry a tool, such as a grinding wheel, on one :projecting end thereof, an electric motor for driving said spindle mounted on the other end of said bracket in substantially diametrically opposed counterbalancing relation to said spindle, said motor having an armature shaft, a drive connection between the armature shaft of said motor and the other end of said spindle, a pair of spaced parallel rods slidably mounted in holes provided therefor in said clamp in radially spaced parallel relation to said overarm, said rods being attached at their outer ends to said bracket for adjustably supporting said bracket relative to the clamp and overarm, racks on said rods, a cross-shaft mounted in said clamp carrying pinions meshing with said racks, manually'operable means for turning said cross-shaft, gibs of V-shaped crosssection extending lengthwise in the holes in said clamp and slidably received in V-shaped grooves provided in said rods extending lengthwise thereof, and adjustable screw means threaded in the clamp to adjust the gibs radially relative to the grooves in said rods and to clamp said rods in adjusted position relative to said clamp by means of said gibs.

4. An attachment for milling machines comprising an upright bracket of elongated form having a clamp intermediate its ends on a horizontal axis for support adjustably on the horizontal overarm of a milling machine, a substantially horizontal spindle rotatably mounted in one end portion of said bracket and adapted to carry a tool, such as a grinding wheel, on one projecting end thereof, an electric motor for driving said spindle mounted on the other end of said bracket in substantially diametrically counterbalancing opposed relation to said spindle, said motor having an armature shaft, a drive connection between the armature shaft of said motor and the other end of said spindle, a pair of spaced parallel rods slidably mounted in holes provided therefor in said clamp in radially spaced parallel relation to said overarm, said rods being attached at their outer ends'to said bracket for adjustably supporting said bracket relative to the clamp and overarm, gibs of V-shaped cross-section extending lengthwise in the holes in said clamp and slidably received in V-shaped grooves provided in said rods extending lengthwise thereof, and adjustable screw means threaded in the clamp to adjust the gibs radially relative to the grooves in said rods and to clamp said rods in adjusted position relative to said clamp by means of said gibs.

5. An attachment for milling machines comprising an upright bracket of elongated form having a clamp intermediate its ends on a horizontal axis for support adjustably on the horizontal overarm of a milling machine, a substantially horizontal spindle rotatably mounted in one end portion of said bracket and adapted to carry a tool, such as a grinding wheel, on one projecting end thereof, an electric motor for driving said spindle mounted on the other end of said bracket in substantially diametrically opposed counterbalancing relation to said spindle, said motor having an armature shaft, a drive connection between the armature shaft of said motor and the other end of said spindle, a pair of spaced parallel rods slidably mounted in holes provided therefor in said clamp in radially spaced parallel relation to said overarm, said rods being attached at their outer ends to said bracket for adjustably supporting said bracket relative to the clamp and overarm, an upright shaft rotatable in a bearing provided therefor in said bracket on an axis at right angles to the overarm, a support for the motor fixed on the upper projectin end of said shaft, a support for the horizontal spindle fixed on the lower projecting end of said shaft whereby the horizontal spindle may be rotatably adjusted with the motor relative to the bracket around said shaft as an axis, and means for clamping the shaft in adjustably fixed relationv to said bracket.

ARTHUR P. DREDSKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,366,932 Pihl Feb. 1, 1921 1,511,677 Page Oct. 14, 1924 1,832,997 Reid Nov. 24, 1931 1,857,047 Enochson May 3, 1932 1,924,958 Patterson Aug. 29, 1933 1,979,140 Casey Oct. 30, 1934 2,022,819 Musgrave Dec. 3, 1935 2,132,640 Mummert Oct. 11, 1938 2,140,580 Hatohman Dec. 20, 1938 2,174,146 Turrettini Sept. 26, 1939 2,199,704 Jaenichen May 7, 1940 2,239,639 Amidon Apr. 22, 1941 2,305,889 McQuade Dec. 22, 1942 2,324,416 Murray July 13, 1943 2,386,283 Wiken et a1 Oct. 9, 1945 

